The present invention relates to vehicle bumper systems, and more specifically relates to B-shaped reinforcement beams with a face wall having a particular radiused shape over its tubular sections and a recess in the center web between the tubular sections.
It is known to manufacture B-shaped reinforcement beams for use in vehicle bumper systems. For example, see Sturrus U.S. Pat. No. 5,395,036, issued Mar. 7, 1995. However, “standard” B-section beams (historically) have a relatively flat front wall (often called its “face”) with tightly radiused corners at their upper and lower edges. The “standard” B-section beams (as exemplified by Sturrus '036) further include a relatively flat center web positioned at a location vertically aligned with upper and lower portions of the front wall. However, it has been discovered that a “standard B-section beam” has a tendency to prematurely buckle during an impact, due in part to high stress concentration in the tight radius areas and due in part to buckle-type failure occurring in the planar front wall. This buckling results in premature load drop due to premature failure of the entire B-beam, and in turn may result in a need for longer strokes for the bumper system and higher “back of beam” (BOB) clearance requirements.